The subject matter disclosed herein relates to rotary machines, and more particularly to a clearance control system for adjusting the clearance between a stationary component and a rotary component of the rotary machine, as well as a method of adjusting the clearance.
In certain applications, a clearance may exist between components that move relative to one another. For example, a clearance may exist between rotary and stationary components in a rotary machine, such as a compressor, a turbine, or the like. The clearance may increase or decrease during operation of the rotary machine due to temperature changes and other factors. A smaller clearance may improve performance and efficiency in a compressor or turbine, because less working fluid leaks between blades and a surrounding structure, such as a shroud, for example. However, a smaller clearance also increases the potential for a rub condition between the rotary and stationary components. For example, the potential for a rub condition may increase during transient conditions and decrease during steady state conditions. Unfortunately, existing systems do not adequately control clearance in rotary machines. Manipulating the response of surrounding structures include a fast response during startup to avoid rubbing, however, an associated fast response during shutdown may result in rubbing and/or pinching during shutdown or subsequent restart. Conversely, slow responses of the surrounding structures may lead to rubbing and/or pinching during a cold start transient.